This application is a §371 National Stage of PCT International Application No. PCT/IB2009/055367 filed Nov. 26, 2009. PCT/IB2009/055367 claims priority to IT Application No. BO2008A000720 filed Nov. 28, 2008. The entire contents of these applications are incorporated herein by reference.
The present invention relates to machines and methods for filling capsules or similar elements with pharmaceutical products. In particular it refers to a filling machine of the single-turret type and comprises a weighing device that is suitable for determining the net weight of the capsules, i.e. the weight of the dosed product.
In the processes of filling capsules of hard gelatine with pharmaceutical products, for example products in liquid, powder, granular or tablet form, the use of weighing apparatuses or devices is known that are placed downstream of the filling machine to measure the weight of the dosed product inside the capsules.
It is necessary to check weight both in order to reject from production capsules that are not compliant because they contain a quantity of product outside the permitted dosing tolerance range and in order to correct possible excesses or defects in dosing the product, by acting in feedback manner on a filling unit of the machine.
In the pharmaceutical field especially, it is important to check that the quantity of product introduced into the single capsules is exactly what is requested, with very narrow tolerance ranges.
In the case of filling processes in which the weight of the capsules is considerably less than the weight of the product to be dosed—so-called “macrodoses”—the capsules are generally weighed only once at the end of dosing. As the weight of the empty capsules is known and contained within a preset tolerance range, which is indicated and guaranteed by the manufacturers of the capsules, it is possible, from the measurement of the weight of the filled capsule (gross weight) subtracting the known weight of the empty capsule (tare weight), calculating the weight of the dosed product (net weight) with a certain degree of accuracy.
In this case in fact, variations in the weight of the empty capsules are negligible and fully contained within the tolerance range for the dosed product.